1. Field of the Invention
The present invention relates to a method and die assembly apparatus for continuously extruding and filling a snack product.
2. Description of the Background Art
Continuous processes for extruding and filling snack products are known. For example, commonly owned U.S. Pat. No. 3,615,675 to Wisdom discloses forming a light puffed food product having a core filled with edible paste-like material. The product is formed by extruding a cylindrical collet around a long fill tube whose diameter increases progressively toward the tube outlet. The collet is cooled as it moves along the internal fill tube and filling is injected into the collet at the end of the tube to form a core. The collet is later cut into product pieces. The apparatus described in the Wisdom patent utilizes a filling tube having a length which is more than 50 times the tube's diameter, the physical properties of the tube and the surrounding atmosphere being used to cool the collet. A tube of such length is necessary when filling puff-extruded cylindrical collets because of the difficulty of steam escaping from a cylindrical collet. Moreover, it is extremely difficult to clean the filling tube described in the Wisdom apparatus if it becomes clogged. Since the collet produced is cylindrical, it cannot be determined by visually inspecting a continuous collet if the collet has been filled or not. Unfilled collets due to clogging of the filling tube presents the problem of waste and/or potential consumer dissatisfaction with the product.
U.S. Pat. No. 3,857,963 to Groff et al. discloses a method for forming center-filled chewing gum. During the extrusion of a hollow-centered rope of chewing gum, a center-filling is fed through an inner conduit to the hollow center of the chewing rope downstream of the extruder orifice. Air is vented from the hollow center of the rope upstream through a space between inner and outer orifice conduits.
There remains a need in the art for a method for coextruding a moisture-containing food material and a center filling material without the disadvantages of the prior art.